福島県東部野手上山玄武岩中の超苦鉄質・苦鉄質包有物

抄録

Ultramafic and mafic inclusions, including intermediate ones, up to 3 cm in size found in high magnesian tholeiitic basalts are divided into the following three groups based on the mineral assembalge and texture: 1) poikilitic peridotite and pyroxenite, 2) pyroxenite including webster-ite, clinopyroxenite and orthopyroxenite, and 3) gabbro and diorite. The 1st group consists of euhedral olivine chadacrysts with chrome spinel inclusions, and clinopyroxene and/or orthopyrox-ene oikocrysts. The 2nd one shows equigranular in texture, but the last one does poikilitic and equigranular. Most of them contain interstitial patches composed of plagioclase, magnetite, clinopyroxene and glass. Petrographic features suggest that these inclusions are cumulates derived from the host magma.